Mark Clarke, the former Conservative parliamentary candidate nicknamed the Tatler Tory, pinned party activist Elliott Johnson to a chair and threatened to "squash" him "like an ant", an inquest heard.

Mr Clarke acted in an intimidating and "potentially criminal" manner toward young Conservative volunteers, the coroner was told, causing a female volunteer to have a nervous breakdown weeks before Johnson's death.

The parents of Elliott Johnson, Ray and Alison Johnson, attend the opening day of the inquest into their son's deathCredit:
David Rose

Johnson, a 21-year-old Conservative activist and political blogger, was found dead on railway tracks in Bedfordshire in September 15, after making allegations about bullying and intimidation by more senior Conservative Party figures.

In the months following Johnson's death, the scandal grew as senior Tory figures became implicated after failing to act on allegations made about Clarke's bullying.

Grant Shapps, the former international development minister and former party chairman, resigned from the front bench last November, saying the "buck should stop with me".

A coroner's inquest in Bedfordshire heard how Johnson had written to his then employers, the right wing think tank Conservative Way Forward (CWF) to complain about a "sinister" altercation with Clarke in a London pub.

Elliott Johnson with Boris JohnsonCredit:
JASON BYE

Johnson alleged that on 12 August last year at the Marquis of Granby, Clarke, 38, pinned him in a chair and hurled abuse at for using a picture on the CWF website without Clarke's permission.

The court heard how ​Johnson alleged that Clarke, one of the organisers of the party’s “Road Trip” youth campaigns, had threatened to reveal that Johnson had a police caution for tweeting about the European election results. However, Johnson's father said that his son had received no such caution.

"Mark said he would use the information to destroy my career and said it would be across front pages unless I apologised," Johnson had told CWF.

He said that Clarke went "ballistic" as his tone "turned sinister".

Elliott Johnson, 21, was found dead on railway tracks in Bedfordshire on September 15Credit:
Jason Bye

"Mark said he had sued lots of people and squashed them like ants when they are small and young and said 'this is what I am going to do to you.' He grabbed my chin to make sure I was looking at him."

Johnson's complaint went on: "People began to notice Mark shouting at me. I was genuinely fearful that he would start to attack me."

Nottingham University graduate Johnson was "deeply upset" by the incident, the court heard.

Paul Abbott, who was then chief executive of the CWF, told how wanted to send the letter on to Conservative Party headquarters, but Johnson later withdrew his complaint.

Giving evidence at the inquest, Abbott told how Clarke's behaviour towards party activists "deteriorated" over the summer.

"What started in July as comparatively low level stupid things became threats in August which by September became things that I think are potentially criminal," he said.

Abbott told how in the weeks before Johnson's death, he was assisting other young activists with "serious complaints" against Clarke, adding that "one of the girls had a nervous breakdown around this time".

Johnson secretly filmed a further altercation in a pub with Clarke and political journalist Andre Walker and sent it to Abbott.

The court heard how at this meeting, Clarke refused to apologise for the earlier incident at the Marquis of Granby.

The court was told Walker then compared Johnson's work at CWF to the pro-Nazi Second World War Vichy regime in France, suggesting that he would come to an "unpleasant end".

I've been bullied by Mark Clarke and betrayed by Andre Walker... Now all my political bridges are burnt.Elliott Johnson

Walker, who was present at the inquest, has previously claimed that he was in a relationship with Johnson up to his death.

A note to Johnson's parents, Ray and Alison, of Wisbech, Cambridgeshire, found after his death was also read out at the hearing.

In it Johnson wrote: "I've been bullied by Mark Clarke and betrayed by Andre Walker... Now all my political bridges are burnt."

Clarke and Walker both deny all wrongdoing.

At an earlier hearing, the Coroner Tom Osborne said he would not examine the claims of bullying and the Conservative party’s response.

He said it was “beyond the proper scope” of the inquest to interrogate Tory party officials over steps being taken to investigate bullying claims.

Johnson's parents said they accepted the Coroner's conclusion that Johnson's death was suicide but vowed to continue their legal fight, saying they have not ruled out taking senior Tories to court.

Speaking outside court Ray Johnson said: "This doesn't end here, this was just the start. "This does not preclude us from taking legal action against those who we believe were responsible for our son's death."

A spokesman for CWF said: "Our staff and volunteers were central to ensuring the complaints against Mark Clarke were taken seriously, not only taking Elliott’s complaint to CCHQ, but also supporting several others who came forward."